Vacuum switch with power fuse

ABSTRACT

A vacuum switch used for switching high voltage capacitive loads comprises a support chassis on which a hollow support insulator is mounted. One or more vacuum interrupters, each comprising an insulated envelope and relatively movable contacts, are mounted on the hollow support insulator. Operating means are mounted on the support chassis and comprises an insulated operating rod which extends through the hollow support insulator for operating the vacuum interrupter(s). A replaceable power fuse is provided. Means, including a stand-off insulator and fuse connectors are provided to mount the switch in parallel physical relationship with the hollow support insulator and to electrically connect the fuse in series circuit with the vacuum interrupter(s). In one embodiment, a single vacuum interrupter is provided and it is disposed in parallel physical relationship with the hollow support insulator. In other embodiments, a plurality of vacuum interrupters are provided which are transversely disposed with respect to the hollow support insulator. In one of the other embodiments, one of the vacuum interrupters is physically located within the stand-off insulator.

O Unlted States Patent 5] 3,671,907 Brunner 1 June 20, 1972 [54] VACUUMSWITCH WITH POWER FUSE K y g 'g y sistant .vaminerwltt organ Inventor:Richard Brunnel't Dedham Mass- AttorneyThomas F. Kirby, Lee H. Kaiserand Robert B. Ben- [73] Assignee: Allis-Chalmers Manufacturing Company,9?

Milwaukee, Wis.

[22] Filed: Nov. 23, 1970 5 ABSTRACT PP .2 92,030 A vacuum switch usedfor switching high voltage capacitive loads comprises a support chassison which a hollow support [52] U S 337/4 200/144 B insulator is mounted,One or more vacuum interrupters, each comprising an insulated envelopeand relatively movable com 2; tacts, are mounted on the hollow supportinsulator. Operating 1 e o m 9 l 0 l i l 2 means are mounted on thesupport chassis and comprises an f insulated operating rod which extendsthrough the hollow support insulator for operating the vacuuminterrupter(s). A [56] Re'mnm Cited replaceable power fuse is provided.Means, including a standoff insulator and fuse connectors are providedto mount the UNITED STATES PATENTS switch in parallel physicalrelationship with the hollow support 3,280,282 10/1966 Rodeseike et al..337/6 insulator and to electrically connect the fuse in series circuit2,914,627 1 1/1959 Eichelberger et al ..337/4 X with the vacuuminterrupteflsl In one embodiment. a single 3,567,887 3 1971 Maloney..200 144 8 vacuum interrupter is P and it is p e in Parallel 3,418,43912/1968 Casey et aL Nico/144B physical relationship with the hollowsupport insulator. in 3,176,100 3/1965 Hana X other embodiments, aplurality of vacuum lnterrupters are 2,862,080 11/1958 Yonkers. ..337179 x P j transversely P the hollow support insulator. In one of theother embodiments, FOREIGN PATENTS 0R PL ONS one of the vacuuminterrupters is physically located within the stand-off insulator.l,095,74l 12/1967 Great Britain ..200/l44 B 1,080,198 8/1967 GreatBritain ..200/ 144 B 6 Claims, 3 Drawing Figures BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates generally toelectrical circuit interruption and switching apparatus. Moreparticularly, it relates to vacuum switches used for switching'highvoltage capacitive loads.

2. Description of the Prior Art Vacuum switches are used for switchinghigh voltage capacitive loads, such as capacitor banks in high voltageelectrical transmission and distribution systems. One type of vacuumswitch comprises a hollow support insulator which is mounted on achassis and on which one or more vacuum interrupters are mounted.Operating means including an insulated rod extending through the hollowsupport insulator effects operation of the vacuum interrupters. Thevacuum interrupters used are to be distinguished from vacuum typecircuit breakers in that the former do not have a substantial capabilityfor interrupting high currents. Therefore, since the vacuum interruptersare exposed to high overcurrent conditions caused by overloads and faultconditions, it has been necessary for safety reasons to provideprotective devices such as fuses or circuit breakers in series with thevacuum switches. Heretofore, these protective devices were mounted on aseparate structure or mounting pad. This approach required numerouscostly components which occupied much space, particularly sinceelectrical clearance and insulation factors had to be taken intoaccount. Therefore, a new approach is desirable with overcomes these andother problems and has additional advantages.

SUMMARY OF THE INVENTION In accordance with the present invention, thereare provided new and improved vacuum switches which comprise asupporting chassis for location in a low potential region. Hollowsupport insulator means are mounted on the chassis and at least onevacuum interrupter is supported in a high potential region by the hollowsupport insulator means. Operating means are provided on the chassis andcomprise an insulating operating rod extending through the hollowsupport insulator means to effect operation of the vacuum interrupter. Areplaceable cartridge type power fuse is provided and means are providedfor supporting the fuse in the high potential region in series with thevacuum interrupter in a manner which requires minimum space usage andaffords maximum accessibility for replacement. Such means comprisestand-oil insulator means transversely disposed with respect to thehollow support insulator means; first fuse connector means on thestand-off insulator means; and second fuse connector means supported byone end of the vacuum interrupter. The fuse is disposed in generallyparallel relationship with the hollow support insulator to providecompactness and accessibility. In accordance with one aspect of theinvention a single interrupter is provided and it is in axial alignmentwith respect to the hollow support insulator. In accordance with anotheraspect of the invention one or more interrupters are provided which aretransversely disposed with respect to the hollow support insulatorwhereas the fuse remains in parallel relationship with the latter. Inaccordance with still another aspect of the invention the stand-offinsulator means is hollow and one of a plurality of vacuum interruptersis disposed therein.

OBJECTS It is an object of the invention to provide new and improvedvacuum switches and, particularly, those of a type which comprise one ormore series connected vacuum interrupters and replaceable fuses.

Another object is to provide switches of the aforesaid character whichare well-suited for application in a wide range of voltage and currentratings.

Another object is to provide such switches which are extremely compactand require no more space and only a few more components than vacuumswitches which do not comprise replaceable fuses.

Another object is to provide such switches in which the fuse is easilyaccessible from the ground level for removal and replacement by ahook-stick device.

Another object is to provide such switches which pose no new oradditional electrical clearance problems in a system wherein they areinstalled.

Another object is to provide such switches which are easily andeconomically manufactured, which use relatively low cost standardizedhardware and components, which are easily serviced and maintained, andwhich are reliable in use.

Other objects and advantages of the invention will hereinafier appear.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing illustratesseveral preferred embodiments of the invention, but it is to beunderstood that the embodiments illustrated are susceptible ofmodifications with respect to details thereof without departing from thescope of the appended claims.

In the drawing:

FIG. 1 is a side elevational view of a first embodiment of a vacuumswitch in accordance with the invention which employs a single vacuuminterrupter and a single fuse;

FIG. 2 is a side elevational view of a second embodiment which employstwo vacuum interrupters and a single fuse; and

FIG. 3 is a side elevational view of a third embodiment which employsfour vacuum interrupters and a single fuse.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment Referring toFIG. 1 of the drawing, the numeral 10 designates a first embodiment of avacuum switch in accordance with the invention which is rated, forexample, at 15.5 KV. Switch 10 comprises support chassis means such as ametal housing 12 which is understood to be adapted for disposition in aregion of low potential, normallyground potential. Hollow supportinsulator means comprising a skirted hollow ceramic insulator 14 ismounted with its first or lower end 16 adjacent and secured to housing12. An electrically conductive member or bracket 18 is secured to thesecond or upper end 20 of insulator l4 and is provided with first orline terminal means 19. Stand-off insulator means comprising a skirtedsolid ceramic insulator 22 is mounted in transverse relationship withrespect to insulator 14 with its first or inner end 24 adjacent andsecured to upper end 20 of insulator 14 by means of bracket 18. Anelectrically conductive member or bracket 26 is secured to the second orouter end 28 of insulator 22. Bracket 26 is provided with second or loadterminal means 27 and with a first fuse connector means 29. A vacuuminterrupter 30 is mounted in a region of high potential with its firstor lower end 32 adjacent and secured to upper end 20 of insulator 14 bymeans of bracket 18. Interrupter 30 is axially aligned with the axis ofinsulator l4. Interrupter 30 comprises an evacuated insulating envelope34 in which a stationary contact 36 and a movable contact 38 aremounted. Envelope 34 is disposed in and protected by an insulatedhousing 40, preferably of transparent material such as Plexiglass. Anelectrically conductive bracket 42 has one end 46 supported by thesecond or upper end 48 of interrupter 30 and is electrically connectedto stationary contact 36. The other end 50 of bracket 42 is providedwith a second fuse connector means 52. Fuse 44 is a cartridge type orelongated tubular type power fuse of suitable rating having an insulatedhousing 54 and electrically conductive first and second end members orferrules S6 and 58 which engage the fuse connector means 29 and 52,respectively. The first end ferrule 56 of fuse 44 is mounted adjacentthe second end 28 of stand-off insulator 22 and the second end ferrule58 of the fuse is mounted adjacent or in line with the second end 48 ofvacuum interrupter 30 so that the fuse is parallel to the axis of hollowsupport insulator 14 and in a vertical disposition with respect to theground so as to be accessible. Fuse 44 is understood to be removable orreplaceable from the ground by means of a hook-stick and is providedwith a hook-stick ring 60 on ferrule 58. Stationary contact 36 ofinterrupter 34 is electrically connected to bracket 42 and movablecontact 38 of interrupter 34 is electrically connected to bracket 18.Switch operating means comprising a linkage 64 disposed in housing 12are provided and the linkage is connected to a reciprocably movableinsulated operating rod 66 which extends from housing 12, through hollowinsulator l4 and is mechanically connected to movable contact 38 ofinterrupter 30. Linkage 64 is adapted to move to open and closedposition in response to suitable electrical, mechanical, orelectromechanical control. means, not shown. Downward movement of rod 66effected by linkage 64 effects separation of contacts 38 and 36 ofinterrupter 30 and opening of switch 10. Upward movement of rod 66effects closing of contacts 38 and 36 of interrupter 30 and closing ofswitch 10. When switch is closed, a current path exists from lineterminal 19, through movable contact 38, stationary contact 36,conductor 42, fuse connector 52, fuse 44 and fuse connector 29, to loadterminal 27. Fuse 44 is appropriately rated to protect againstovercurrent conditions to which switch 10 may be subjected. Since fuse44 is in series circuit with interrupter 30, if the fuse flows, switch10 is opened automatically. When this occurs, interrupter 30 is openedin response to actuation of the operating means by operating personnel,fuse 44 is then removed by means of a hook-stick and a new one installedin its place, and interrupter 30 is then reclosed to reestablish thecircuit.

Second Embodiment Referring to FIG. 2 of the drawing, the numeral 110designates a second embodiment of a vacuum switch in accordance with theinvention which is rated, for example, at 34.5 KV. Switch 1 10 comprisessupport chassis means such as a metal housing 112 which is attached to achannel iron beam 113 and understood to be adapted for disposition in aregion of low potential, normally ground potential. Hollow supportinsulator means comprising a skirted hollow ceramic insulator 114 ismounted with its first or lower end 116 adjacent and secured to housing112. A housing 118 is secured to the second or upper end 120 ofinsulator 114 and supports a first vacuum interrupter 130 and a secondvacuum interrupter 131.

Second interrupter 131 is provided with first or line terminal means 119which is connected to a stationary contact 117 of interrupter 131.Stand-off insulator means comprising a skirted solid ceramic insulator122 is mounted in transverse relationship with respect to insulator 1 14with its first or inner end 124 adjacent lower end 1 16 of insulator 114and secured to housing 1 12. An electrically conductive member orbracket 126 is secured to the second or outer end 128 of insulator 122.Bracket 126 is provided with second or load terminal means 127 and witha first fuse connector means 129. First vacuum interrupter 130, which isunderstood to be identical to interrupter 131 is mounted in a region ofhigh potential with its first or inner end 132 adjacent and secured toupper end 120 of insulator 114 by means of a housing 118 in which motiontranslating means 137 are located. interrupters 130 and 131 aretransversely disposed with respect to the axis of insulator 114.lnterrupter 130, which is similar to interrupter 131, comprises anevacuated insulating envelope 134 in which a stationary contact 136 anda movable contact 138 are mounted. Envelope 134 is disposed in andprotected by an insulated housing 140, preferably of transparentmaterial such as Plexiglass. An electrically conductive second fuseconnector means 152 is supported by the second or outer end 148 ofinterrupter 130 and is electrically connected to stationary contact 136thereof. A cartridge type or elongated tubular type power fuse 144 ofsuitable rating and having an insulated housing 154 and electricallyconductive first and second end members or ferrules 156 and 158 engagesthe fuse connector means 129 and 152, respectively. The first endferrule 156 of fuse 144 is mounted adjacent the second end 128 ofstand-off insulator 122 and the second end ferrule 158 of the fuse ismounted adjacent the second end 148 of vacuum interrupter 130 so thatthe fuse is parallel to the axis of hollow support insulator 14 buttransverse to interrupter 130. Fuse 144 is understood to be removable orreplaceable from the ground by means of a hook-stick and is providedwith a hook-stick ring 160 on ferrule 158. Movable contact 138 ofinterrupter 134 is electrically connected to a movable contact 135 ofinterrupter 131 by a flexible conductor 139. Switch operating meanscomprising a linkage 164 disposed in housing 112 are provided and thelinkage is connected to a reciprocably movable insulated operating rodl66 which extends from housing 112, through hollow insulator l 14 andinto housing 118 wherein it connects to motion translating means 137which comprises a cam plate 141. Cam plate 141 engages the movablecontacts 138 and 135 of interrupter 130 and 131, respectively. Linkage164 is adapted to move to open and closed position in response tosuitable electrical, mechanical, or electromechanical control means, notshown. Downward movement of rod 166 effected by linkage 164 elTectsseparation of contacts 138 and 135 of interrupters 130 and 131,respectively, and opening of switch 110. Upward movement of rod 166effects closing of contacts 138 and 135 of interrupters 130 and 131,respectively, and closing of switch 110. When switch is closed, acurrent path exists from line terminal 119, through stationary contact 117 and movable contact 135 of interrupter 131, through conductor 139,through movable contact 138 and stationary contact 136 of interrupter130, fuse connector 152, fuse 144 and fuse connector 129, to loadterminal 127. Fuse 144 is appropriately rated to protect againstover-current conditions to which switch 110 may be subjected. Since fuse144 is in series circuit with interrupters and 131, if the fuse blows,switch 110 is opened automatically. When this occurs, interrupters 130and 131 are opened in response to actuation of the operating means byoperating personnel, fuse 144 is then removed by means of a hook-stickand a new one installed in its place, and interrupters 130 and 131 arethen reclosed to reestablish the circuit.

Third Embodiment REferring to FIG. 3 of the drawing, the numeral 210designates a third embodiment of a vacuum switch in accordance with theinvention which is rated, for example, at 69 KV. Switch 210 comprises ametal housing 212, a hollow support insulator means including aninsulator 214, a housing 216, operating means comprising a linkage 264having an insulated operating rod 266, and a motion translating means237 similar to the elements designated l12,1l4,l16,164,166 and 137,respectively, hereinbefore described in connection with FIG. 2. Inswitch 210 the hollow support insulator means further comprises a secondhollow support insulator 214a which is mounted on housing 216 in axialalignment with insulator 214. In addition, a second housing 2160 ismounted on the upper end of insulator 214a and a motion translatingmeans 2370 is disposed therein. The motion translating means 237 and237a are connected by an insulated operating rod 2660. Switch 210comprises a first pair of series connected vacuum interrupters 220 and222 disposed on opposite sides of housing 216 and a second pair ofseries connected vacuum interrupters 224 and 226 disposed on oppositesides of hous ing 216a. The vacuum interrupters 220 and 222; 224 and 226are understood to be similar to the vacuum interrupters 131 and 130,respectively, described in connection with FIG. 2. In switch 210 aninsulated housing 228 for vacuum interrupter 222 also serves as astand-off insulator for a replaceable fuse 244 which is similar inconstruction to fuse 44 hereinbefore described in connection withFIG. 1. The outer ends of the interrupters 222 and 224 are provided withfirst and second fuse connector means 229 and 252, respectively. FUse244 forms a series connection between the interrupters 222 and 224. Theouter ends of the interrupters 226 and 220 are provided with first(line) and second (load) terminals 219 and 227, respectively. Linkage264 is adapted to move to open and closed position in response tosuitable electrical, mechanical, or electromeehanical control means, notshown. Downward movement of rods 226 and 226a effected by linkage 264efl'ects separation of the contacts of interrupters 220,222,224 and 226and opening of switch 210. Upward movement of rods 226 and 2264 efi'ectsclosing of the contacts of interrupters 220,222,224 and 226 and closingof switch 210. When switch 210 is closed, a current path exists fromline terminal 219, through interrupters 226 and 224, fuse connector 252,fuse 244, fuse connector 229, and interrupters 222 and 220, to loadterminal 227. Fuse 244 is appropriately rated to protect againstovercurrent conditions to which switch 210 may be subjected. Since fuse244 is in series circuit with the interrupters 226, 224, 222 and 220, ifthe fuse blows, switch 210 is opened automatically. When this occurs,all interrupters 220, 222, 224 and 226 are opened in response toactuation of the operating means by operating personnel, fuse 244 isthen removed by means of a hook-stick and a new one installed in itsplace, and the interrupters are then reclosed to reestablish thecircuit.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A vacuum switch comprising: a support chassis, hollow supportinsulator means mounted on said chassis, at least one vacuum interruptersupported by said support insulator means, vacuum interrupter operatingmeans on said support chassis and comprising an insulating operating rodextending through said hollow support insulator means to effectoperation of said vacuum interrupter, a replaceable cartridge fuse, andmeans for supporting said fuse on an axis which is parallel to the axisof said hollow support insulator means and for connecting said fuse inseries with said vacuum interrupter, said means comprising: stand-offinsulator means having one end supported adjacent the end of said hollowsupport insulator means most remote from said support chassis anddisposed transversely with respect to said hollow support insulatormeans, first fuse connector means on said stand-off insulator means, andsecond fuse connector means supported by one end of said vacuuminterrupter.

2. A switch according to claim 1 wherein said vacuum interrupter isdisposed on an axis which is parallel to said fuse axis.

3. A switch according to claim 2 comprising first terminal meanselectrically connected to said vacuum interrupter at the end of thelatter closest to said hollow support insulator means and furthercomprising second terminal means electrically connected to said firstfuse connector means.

4. A switch according to claim 3 wherein said first terminal means isintegral with a conductive support which supports said stand-offinsulator means and wherein said second terminal means is integral withsaid first fuse connector means.

5. A vacuum switch comprising:

a support chassis;

at least one hollow support insulator means mounted on said chassis; atleast one pair of series connected vacuum interrupters carried by saidsupport insulator means;

vacuum interrupter operating means extending through said hollow supportinsulator means to effect operation of said vacuum interrupters;

at least a pair of stand-01f insulator means carried by said chassis anddisposed transversely with respect to said hollow support insulatormeans, at least one of said stand-ofi insulator means serving as aninsulator housing for at least one of said series connected vacuuminterrupters;

a replaceable cartridge fuse; and,

fuse connector means carried by said stand-off insulator means andoperable to releasably receive and connect said cartridge fuse in serieswith said vacuum interrupters.

6. A vacuum switch comprising:

a support chassis;

at least one hollow support insulator means mounted on said chassis;

a plurality of vacuum interrupters carried by said support insulatormeans;

vacuum interrupter operating means extending through said hollow supportinsulator means and operably connected to effect operation of saidvacuum interrupters;

a plurality of stand-off insulator means carried by said chassis anddisposed transversely with respect to said hollow support insulatormeans, said stand-ofi insulator means being operable to serve asinsulator housing means for said vacuum interrupters;

a replaceable cartridge fuse; and,

fuse connector means carried by said stand-off insulator means andoperable to releasably secure and connect said cartridge fuse in seriesbetween at least two of said vacuum interrupters in a manner to serve asa series connector therebetween.

1. A vacuum switch comprising: a support chassis, hollow supportinsulator means mounted on said chassis, at least one vacuum interruptersupported by said support insulator means, vacuum interrupter operatingmeans on said support chassis and comprising an insulating operating rodextending through said hollow support insulator means to effectoperation of said vacUum interrupter, a replaceable cartridge fuse, andmeans for supporting said fuse on an axis which is parallel to the axisof said hollow support insulator means and for connecting said fuse inseries with said vacuum interrupter, said means comprising: stand-offinsulator means having one end supported adjacent the end of said hollowsupport insulator means most remote from said support chassis anddisposed transversely with respect to said hollow support insulatormeans, first fuse connector means on said stand-off insulator means, andsecond fuse connector means supported by one end of said vacuuminterrupter.
 2. A switch according to claim 1 wherein said vacuuminterrupter is disposed on an axis which is parallel to said fuse axis.3. A switch according to claim 2 comprising first terminal meanselectrically connected to said vacuum interrupter at the end of thelatter closest to said hollow support insulator means and furthercomprising second terminal means electrically connected to said firstfuse connector means.
 4. A switch according to claim 3 wherein saidfirst terminal means is integral with a conductive support whichsupports said stand-off insulator means and wherein said second terminalmeans is integral with said first fuse connector means.
 5. A vacuumswitch comprising: a support chassis; at least one hollow supportinsulator means mounted on said chassis; at least one pair of seriesconnected vacuum interrupters carried by said support insulator means;vacuum interrupter operating means extending through said hollow supportinsulator means to effect operation of said vacuum interrupters; atleast a pair of stand-off insulator means carried by said chassis anddisposed transversely with respect to said hollow support insulatormeans, at least one of said stand-off insulator means serving as aninsulator housing for at least one of said series connected vacuuminterrupters; a replaceable cartridge fuse; and, fuse connector meanscarried by said stand-off insulator means and operable to releasablyreceive and connect said cartridge fuse in series with said vacuuminterrupters.
 6. A vacuum switch comprising: a support chassis; at leastone hollow support insulator means mounted on said chassis; a pluralityof vacuum interrupters carried by said support insulator means; vacuuminterrupter operating means extending through said hollow supportinsulator means and operably connected to effect operation of saidvacuum interrupters; a plurality of stand-off insulator means carried bysaid chassis and disposed transversely with respect to said hollowsupport insulator means, said stand-off insulator means being operableto serve as insulator housing means for said vacuum interrupters; areplaceable cartridge fuse; and, fuse connector means carried by saidstand-off insulator means and operable to releasably secure and connectsaid cartridge fuse in series between at least two of said vacuuminterrupters in a manner to serve as a series connector therebetween.